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Adsorbate-induced curvature and stiffening of graphene.

Svatek SA, Scott OR, Rivett JP, Wright K, Baldoni M, Bichoutskaia E, Taniguchi T, Watanabe K, Marsden AJ, Wilson NR, Beton PH - Nano Lett. (2014)

Bottom Line: This effect arises from a curvature-dependent variation of a moiré pattern due to the mismatch of the carbon-carbon separation in the adsorbed molecule and the period of graphene.The effect is observed when graphene is transferred onto a deformable substrate, which in our case is the interface between water layers adsorbed on mica and an organic solvent, but is not observed on more rigid substrates such as boron nitride.Our results show that molecular adsorption can be influenced by substrate curvature, provide an example of two-dimensional molecular self-assembly on a soft, responsive interface, and demonstrate that the mechanical properties of graphene may be modified by molecular adsorption, which is of relevance to nanomechanical systems, electronics, and membrane technology.

View Article: PubMed Central - PubMed

Affiliation: School of Physics and Astronomy, University of Nottingham , Nottingham NG7 2RD, United Kingdom.

ABSTRACT
The adsorption of the alkane tetratetracontane (TTC, C44H90) on graphene induces the formation of a curved surface stabilized by a gain in adsorption energy. This effect arises from a curvature-dependent variation of a moiré pattern due to the mismatch of the carbon-carbon separation in the adsorbed molecule and the period of graphene. The effect is observed when graphene is transferred onto a deformable substrate, which in our case is the interface between water layers adsorbed on mica and an organic solvent, but is not observed on more rigid substrates such as boron nitride. Our results show that molecular adsorption can be influenced by substrate curvature, provide an example of two-dimensional molecular self-assembly on a soft, responsive interface, and demonstrate that the mechanical properties of graphene may be modified by molecular adsorption, which is of relevance to nanomechanical systems, electronics, and membrane technology.

No MeSH data available.


Related in: MedlinePlus

(a–c)TTC on G/hBN. (a) Lamellar rows of TTC on G/BN; the G/BN moirépattern is also resolved. Scale bar: 20 nm (sample voltage −1V, tunnel current 0.07 nA). (b) High resolution STM image of lamellarrows. Scale bar: 5 nm (−1 V, 0.1 nA). (c) Zoom of (b) showingatomic resolution. (d) Schematic of adsorption of an n-alkane on graphene. Due to the mismatch in lattice constants, −CH2– groups are adsorbed at different local environmentson the flat graphene. (e) TTC on G/mica. The lamellar structure runscontinuously across several 100 nm and over terrace edges introducedby water layers. Scale bar: 60 nm (−1 V, 0.15 nA). (f) TTCon G/mica. Strong anisotropy of the shape of trapped water is apparentin areas where more than three layers of water are trapped. Scalebar: 10 nm (−1 V, 0.15 nA). Inset: Fourier transform of imageshowing an elliptical central spot indicating deformation of underlyinggraphene; the molecular structure along the lamellae gives rise tothe spots identified by arrows; inverse length scale bar 1 nm–1. (g) Profile along marked line in (e) showing stepheights across water layer. (h) Histogram of heights for differentnumber of water layers trapped at the G/mica interface indicatingan increasing roughness for a higher number of trapped water layers.(i) Differential image of TTC on G/mica with >3 layers of watershowing that the expected molecular arrangement within the lamellarrows; the undifferentiated image is included in Supporting Information. Scale bar: 6 nm (−1 V, 0.15nA).
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fig1: (a–c)TTC on G/hBN. (a) Lamellar rows of TTC on G/BN; the G/BN moirépattern is also resolved. Scale bar: 20 nm (sample voltage −1V, tunnel current 0.07 nA). (b) High resolution STM image of lamellarrows. Scale bar: 5 nm (−1 V, 0.1 nA). (c) Zoom of (b) showingatomic resolution. (d) Schematic of adsorption of an n-alkane on graphene. Due to the mismatch in lattice constants, −CH2– groups are adsorbed at different local environmentson the flat graphene. (e) TTC on G/mica. The lamellar structure runscontinuously across several 100 nm and over terrace edges introducedby water layers. Scale bar: 60 nm (−1 V, 0.15 nA). (f) TTCon G/mica. Strong anisotropy of the shape of trapped water is apparentin areas where more than three layers of water are trapped. Scalebar: 10 nm (−1 V, 0.15 nA). Inset: Fourier transform of imageshowing an elliptical central spot indicating deformation of underlyinggraphene; the molecular structure along the lamellae gives rise tothe spots identified by arrows; inverse length scale bar 1 nm–1. (g) Profile along marked line in (e) showing stepheights across water layer. (h) Histogram of heights for differentnumber of water layers trapped at the G/mica interface indicatingan increasing roughness for a higher number of trapped water layers.(i) Differential image of TTC on G/mica with >3 layers of watershowing that the expected molecular arrangement within the lamellarrows; the undifferentiated image is included in Supporting Information. Scale bar: 6 nm (−1 V, 0.15nA).

Mentions: We have investigated the adsorptionof TTC on graphene (G) transferred to either exfoliated hexagonalboron nitride (hBN) flakes on a supporting SiO2 layer13 or ontomica.14 STM images of TTC on G/hBN and G/mica (Figure 1) show lamellar rows of molecules that run continuously over grapheneboth on the relatively smooth hBN and also on the rougher G/mica substrate.The lamellar arrangement is most clearly resolved for TTC on G/hBN(Figure 1a–c) and is very similar tothe arrangement for analogue alkanes15−17 adsorbed on graphite.The rows in Figure 1a are superposed on a hexagonalmoiré pattern arising from the orientational mismatch betweenthe transferred graphene and the hBN supporting substrate.18−20 The presence of the moiré pattern confirms that the G andhBN are in direct contact, indicating that the adhesion between thesesurfaces is maintained in the presence of the TTC/tetradecane solution.


Adsorbate-induced curvature and stiffening of graphene.

Svatek SA, Scott OR, Rivett JP, Wright K, Baldoni M, Bichoutskaia E, Taniguchi T, Watanabe K, Marsden AJ, Wilson NR, Beton PH - Nano Lett. (2014)

(a–c)TTC on G/hBN. (a) Lamellar rows of TTC on G/BN; the G/BN moirépattern is also resolved. Scale bar: 20 nm (sample voltage −1V, tunnel current 0.07 nA). (b) High resolution STM image of lamellarrows. Scale bar: 5 nm (−1 V, 0.1 nA). (c) Zoom of (b) showingatomic resolution. (d) Schematic of adsorption of an n-alkane on graphene. Due to the mismatch in lattice constants, −CH2– groups are adsorbed at different local environmentson the flat graphene. (e) TTC on G/mica. The lamellar structure runscontinuously across several 100 nm and over terrace edges introducedby water layers. Scale bar: 60 nm (−1 V, 0.15 nA). (f) TTCon G/mica. Strong anisotropy of the shape of trapped water is apparentin areas where more than three layers of water are trapped. Scalebar: 10 nm (−1 V, 0.15 nA). Inset: Fourier transform of imageshowing an elliptical central spot indicating deformation of underlyinggraphene; the molecular structure along the lamellae gives rise tothe spots identified by arrows; inverse length scale bar 1 nm–1. (g) Profile along marked line in (e) showing stepheights across water layer. (h) Histogram of heights for differentnumber of water layers trapped at the G/mica interface indicatingan increasing roughness for a higher number of trapped water layers.(i) Differential image of TTC on G/mica with >3 layers of watershowing that the expected molecular arrangement within the lamellarrows; the undifferentiated image is included in Supporting Information. Scale bar: 6 nm (−1 V, 0.15nA).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4326047&req=5

fig1: (a–c)TTC on G/hBN. (a) Lamellar rows of TTC on G/BN; the G/BN moirépattern is also resolved. Scale bar: 20 nm (sample voltage −1V, tunnel current 0.07 nA). (b) High resolution STM image of lamellarrows. Scale bar: 5 nm (−1 V, 0.1 nA). (c) Zoom of (b) showingatomic resolution. (d) Schematic of adsorption of an n-alkane on graphene. Due to the mismatch in lattice constants, −CH2– groups are adsorbed at different local environmentson the flat graphene. (e) TTC on G/mica. The lamellar structure runscontinuously across several 100 nm and over terrace edges introducedby water layers. Scale bar: 60 nm (−1 V, 0.15 nA). (f) TTCon G/mica. Strong anisotropy of the shape of trapped water is apparentin areas where more than three layers of water are trapped. Scalebar: 10 nm (−1 V, 0.15 nA). Inset: Fourier transform of imageshowing an elliptical central spot indicating deformation of underlyinggraphene; the molecular structure along the lamellae gives rise tothe spots identified by arrows; inverse length scale bar 1 nm–1. (g) Profile along marked line in (e) showing stepheights across water layer. (h) Histogram of heights for differentnumber of water layers trapped at the G/mica interface indicatingan increasing roughness for a higher number of trapped water layers.(i) Differential image of TTC on G/mica with >3 layers of watershowing that the expected molecular arrangement within the lamellarrows; the undifferentiated image is included in Supporting Information. Scale bar: 6 nm (−1 V, 0.15nA).
Mentions: We have investigated the adsorptionof TTC on graphene (G) transferred to either exfoliated hexagonalboron nitride (hBN) flakes on a supporting SiO2 layer13 or ontomica.14 STM images of TTC on G/hBN and G/mica (Figure 1) show lamellar rows of molecules that run continuously over grapheneboth on the relatively smooth hBN and also on the rougher G/mica substrate.The lamellar arrangement is most clearly resolved for TTC on G/hBN(Figure 1a–c) and is very similar tothe arrangement for analogue alkanes15−17 adsorbed on graphite.The rows in Figure 1a are superposed on a hexagonalmoiré pattern arising from the orientational mismatch betweenthe transferred graphene and the hBN supporting substrate.18−20 The presence of the moiré pattern confirms that the G andhBN are in direct contact, indicating that the adhesion between thesesurfaces is maintained in the presence of the TTC/tetradecane solution.

Bottom Line: This effect arises from a curvature-dependent variation of a moiré pattern due to the mismatch of the carbon-carbon separation in the adsorbed molecule and the period of graphene.The effect is observed when graphene is transferred onto a deformable substrate, which in our case is the interface between water layers adsorbed on mica and an organic solvent, but is not observed on more rigid substrates such as boron nitride.Our results show that molecular adsorption can be influenced by substrate curvature, provide an example of two-dimensional molecular self-assembly on a soft, responsive interface, and demonstrate that the mechanical properties of graphene may be modified by molecular adsorption, which is of relevance to nanomechanical systems, electronics, and membrane technology.

View Article: PubMed Central - PubMed

Affiliation: School of Physics and Astronomy, University of Nottingham , Nottingham NG7 2RD, United Kingdom.

ABSTRACT
The adsorption of the alkane tetratetracontane (TTC, C44H90) on graphene induces the formation of a curved surface stabilized by a gain in adsorption energy. This effect arises from a curvature-dependent variation of a moiré pattern due to the mismatch of the carbon-carbon separation in the adsorbed molecule and the period of graphene. The effect is observed when graphene is transferred onto a deformable substrate, which in our case is the interface between water layers adsorbed on mica and an organic solvent, but is not observed on more rigid substrates such as boron nitride. Our results show that molecular adsorption can be influenced by substrate curvature, provide an example of two-dimensional molecular self-assembly on a soft, responsive interface, and demonstrate that the mechanical properties of graphene may be modified by molecular adsorption, which is of relevance to nanomechanical systems, electronics, and membrane technology.

No MeSH data available.


Related in: MedlinePlus